This proposal is a continuation of our research program to establish the role of acrosomal enzymes and microtubules in fertilization in the environment created by the oviduct. Microtubules of the acrosome constitute a possible delivery system for acrosomal lytic enzymes, and we have demonstrated their formation from the matrix both in vitro and in vivo. Our goals include: 1) characterization of low molecular weight glycosaminoglycan(s) of oviduct fluid, which stimulate proacrosin activation, 2) determination of the subcellular localization of sperm antigens for oviductal secretory IgA using indirect staining with peroxidase-labeled antibodies. Secretory IgA is the major immunoglobulin fraction of oviduct fluid, and contains antibodies for acrosin and probably other sperm antigens as well, 3) to study the chemistry of acrosomal microtubules, their physiological function, and the oviduct fluid factors that affect their condensation from the acrosomal matrix.